1. Field of the Invention
The present invention relates to a lighting device or a light-emitting device which includes a light-emitting member exhibiting electroluminescence (EL).
2. Description of the Related Art
A light-emitting element containing an organic compound as a light-emitting body has been expected to be applied to next-generation lighting. A light-emitting element containing an organic compound as a light-emitting body has a feature such as drive at a low voltage with low power consumption.
An organic compound layer included in a light-emitting element includes at least a light-emitting layer. In addition, the organic compound layer can have a stacked-layer structure including a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, and/or the like, in addition to the light-emitting layer.
It is said that, as for a light-emitting mechanism of a light-emitting element, an organic compound layer is provided between a pair of electrodes and voltage is applied to the organic compound layer, so that electrons injected from a cathode and holes injected from an anode are recombined in an emission center of the organic compound layer to form molecular excitons, and the molecular excitons release energy when returning to a ground state; thus, light is emitted. Singlet excitation and triplet excitation are known as excited states, and light emission can probably be achieved through either of the excited states.
Further, since the pair of electrodes and the light-emitting layer are formed as films in such a light-emitting element, surface light emission can easily be obtained by forming a large-area light-emitting element. This is a feature which is hard to obtain in a light source such as an incandescent lamp and an LED (point light sources) or in a fluorescent lamp (line light source), so that the above light-emitting element has a high utility value as a light source such as lighting.
Patent Document 1 discloses a structure where a plurality of light-emitting elements is connected to each other. FIG. 7B of Patent Document 1 shows that the plurality of light-emitting elements is connected to each other only through electrodes thereof.
Patent Document 2 discloses a structure where power supply input concurrently turns on a plurality of organic EL panels. FIGS. 1A and 1B of Patent Document 2 show that wiring circuits are arranged over a substrate for providing panels so as not to intersect with each other. FIGS. 2A to 2C of Patent Document 2 show that the organic EL panel is provided with an anode side current introduction terminal and a cathode side electron introduction pin.